Advertisers maximize the value of advertising by efficiently selecting advertising spaces that effectively produce conversions. In the service industry, users may be more likely to purchase a service or a product at certain times or at a certain length of time before the performance of the service. For example, in certain service industries a user may be unlikely to purchase or reserve a service more than one week ahead of performance of the service while in other service industries a user may be likely to reserve a service months ahead of performance of the service. Additionally, merchants seeking to advertise obtain the most benefit from advertising during times of high availability of merchant services. For example, merchants obtain less benefit from advertising as user reservations for a service approach the capacity of the merchant to provide the service and obtain more benefit from advertising during times at which user reservations are low with respect to the merchant's capacity to provide the service.